Studies have focused on: a) scheduling considerations for tubulin binding agents, specifically vincristine. The results favor infusions over pulse doses, and indicate schedule-dependent synergism with hydroxyurea and adriamycin, respectively. b) Defining the relationship between cell proliferation and the quantitative expression of specialized gene products. An inverse relationship was found between the rate of cell proliferation and the quantitative expression of immunologic surface markers in an early B cell line; similarly, an inverse relationship was observed between cell proliferation and cell content of estrogen receptor. c) Studying the mechanisms underlying clonal evolution as they may relate to clinical and histologic transformation of the lymphomas and as they may relate to the development of drug resistance. Flow cytometry studies in the non-Hodgkin's lymphomas suggest that clonal evolution is fueled by a sequence of i) cell tetraploidization, ii) long term cytogenetic instability of the tetraploid line, iii) progressive chromosome from the tetraploid line, and iv) overgrowth of aneuploid cell lines that are produced by this process.